1. Field of Invention
The present invention relates to the field of the thawing of food products using microwave technology. It is more especially concerned with the methods of thawing that allow foodstuffs in the form of large pieces or blocks, for examples blocks of fish or meat weighing in excess of 20 or even 30 kilograms, to be thawed.
One of the objectives of the present invention is to allow good control over the temperature ensuring even core and surface temperatures avoiding hot spots.
2. Related Art
Specifically, documents proposing pre-cooling of the surface of the product before microwave energy is applied (in order to avoid the phenomena of cooking) are many in number (reference may be made to documents WO2007/039284, GB-1 534 845 or, alternatively, FR-2 405 023), but it is nonetheless found that, in practice, in this industry, real technical difficulties are encountered, which difficulties can be summed up as follows: temperatures that are not even after thawing are found, particularly, it is impossible to achieve a core reference temperature (for example a core temperature of −2° C.) without creating hot spots on the surface of the item, and therefore modifying the quality, structure and appearance of the product.
Because of this, many user sites prefer to leave their blocks (of fish, or even of meat) to thaw naturally in a cold room for 24 to 48 h, which, it will be appreciated, severely penalizes the overall production line, and, incidentally, is not the optimum solution from a food hygiene standpoint either.